AceShowbiz - The death of Richard Simmons is shrouded in mystery which is still awaiting an answer. Although police have stated there "is no foul play" suspected in his passing, his cause of death is unknown and currently under investigation.

On Monday, July 15, the Medical Examiner's Office stated that Richard's cause of death has since been deferred, meaning that an investigation and additional testing are needed. It can take up to three months before a determination is made on the cause of death, according to PEOPLE.

Richard, who chose to live in seclusion in the years leading to his passing, died at his Los Angeles home on Saturday, July 13. Authorities responded to a call from his housekeeper on Saturday morning around 10 A.M. after he was found unresponsive on the floor next to his bed.

According to TMZ, the fitness guru suffered a fall one day before he died. He fell Friday evening in a bathroom at home. When his housekeeper came to help him up, she implored Richard to seek medical attention right away, but he pushed it off because he just wanted to stay home for his birthday.

Richard reportedly felt dizzy before the fall, but refused to go to a doctor, telling his housekeeper maybe he'd go Saturday. The housekeeper helped him back to bed before she found him unresponsive in the morning.

A source told the site Richard showed no obvious or external signs of injury such as bumps, bruises or bleeding following the fall. It's also unclear if whatever caused his dizziness or the fall is directly related to his death. His autopsy has been completed, but the cause of death is pending toxicology test results.

Richard's passing was confirmed by his longtime publicist Tom Estey on Saturday. "The world has truly lost an angel," Tom said of Richard.

On his last tweet prior to his death, Richard, who turned 76 on Friday, July 12, thanked his fans for the birthday wishes he received. "Thank you…I never got so many messages about my birthday in my life! I am sitting here writing emails. Have a most beautiful rest of your Friday," he wrote, signing it off with, "Love, Richard."

His brother Lenny Simmons issued a statement via Richard's social media page on Sunday, asking people not to "be sad" over the fitness icon's death. "Hello Everyone," Lenny began. "I don't want people to be sad about my brother. I want them to remember him for the genuine joy and love he brought to people's lives. He truly cared about people. He called, wrote, and emailed thousands of people throughout his career to offer help."

"So don't be sad. Celebrate his life!" Lenny continued in a separate tweet, before sharing, "He was very excited about all of the upcoming ventures he was working on. We are in shock. Please respect the family at this difficult time."

Meanwhile, tributes have poured in from Richard's celebrity friends, including comedian Pauly Shore, actresses Ricki Lake and Jane Fonda.